IRS Camaros

[mfain]

I've seen several built or "under construction" Camaros with C5/C6 Corvette IRS's (like Tyler's 50/50 project). Does anyone have any reliable, real world performance comparisons between that configuration and a well prepared 3-link set-up. I'm looking for road course comparisons as well as braking performance. I am curious whether the lower rear roll center and the associated higher rear spring rates along with a further-aft center of gravity are making a significant difference in turning performance. Thanks.

Pappy

[mfain]

Looks like I need to narrow my question. Has anyone seen a first gen with C5/C6 independent rear suspension run on a track or autocross, and if so, what was your impression of the performance? Is anyone currently driving or building one of these cars with the intent of serious track time? Tyler?

[Teetoe_Jones]

I've got nothing to go on. You and I have been building our cars for a long time. I will say the reason I decided to do my chassis based on a C5 was because of the Mallett prepped 1999 Corvette that placed in the top 5 in the One Lap of America. I got to drive that car when it got traded in on a Porsche at the dealer I worked for.
That car was stupid fast, handled amazing, and was all I thought a race car should be.

That said, I'm going for an all out race car on my 50/50 project that I drive on the street. I hope that in time I can show cars like Bad Penny, Finch's yellow 70 Camaro, and Shipka's One Lap car some tail lights.

I don't know of any C5 based 1st gens running on the track that we could compare numbers on. There are at least 3 of them on the road though.

Tyler

[mfain]

Thanks Tyler. I'm getting closer -- built some longer LCAs for your ATS spindles and used a deeper offset front wheel -- that gave me a better scrub radius and allowed me to get a 315 on an 11 inch wheel up front with good turn radius. Also some interesting duct work for the oil cooler (inlet, diffuser, and air extractor/nozzle) and I'm finishing the underbody CF tunnels and belly pan. I'll get an update on my build thread soon. We need to get some of these IRS cars on the track, just for the sake of argument.

Pappy

[Vince@Meanstreets]

hey Pap, you have any build threads of your camaro project, love to see it.

Vince

[Silver69Camaro]

It's been said over and over that IRS cars typically only show a benefit over solid axles on bumpy surfaces, and ride quality is noticable on the street. IRS also allows you to adjust camber and toe, both of which are great things to have. But if you know what you are doing, you can do that on a solid axle as well. IRS setups typically wont have pad knockback issues either.

But, our cars just aren't packaged for IRS systems. If you want to chop the rear tin, go for it. Be prepared to run flat-faced wheels and narrow the IRS enough for the correct hub track.

If you want a all-out race car like Tyler, then I think IRS is worth considering. If it's a track day car, I wouldn't bother. But that's just my opinion.

[exwestracer]

I agree with Matt on this (and I'm a BIG fan of IRS). We did a 2nd gen Camaro here at the school awhile back. Full 2X3 frame recessed and welded into the floor, relocated upper control arms, and a complete Nissan 350 multilink IRS.

Track width wasn't really an issue with the Nissan setup, but getting the ride height down to 6" took a lot of cutting. Ditching the cradle might have helped, but would have meant a lot more setup and fabrication for all the mounts.

I've followed Teetoe's build, and they obviously started out with a gutted shell. Either way, it's not easy. Or cheap...

[mfain]

I have already completed the IRS in my car. I was just curious how any of the IRS PT cars were doing on track. I went with an IRS primarily to lower the rear roll center in an attempt to better "balance" the car with respect to front and rear roll angles under lateral g -- to make the rear of the car do more of the cornering work and to get better forward bite off a corner. Most of the new high performance stuff (Corvette, Viper, and even NASCAR) has taken this approach, using a lower roll center and stiffer rear springs and bars. You can also loosen or tighten the car at the track by changing the adjustable roll center. My car is not a Camaro -- it is an old previously straight axle Corvette, but the modifications are somewhat similar to what you have to do with a Camaro. I went with a highly modified C4 approach -- C4 bearing carriers with longer, adjustable forward four link (to minimize C4 roll steer characteristics and to make the instant center and anti-dive/anti-squat adjustable, something you can't do with a C5/C6 set-up without moving the control arm pick-up points); adjustable lower lateral link for both camber and roll center adjustment; a vertically adjustable toe link to fine tune bump steer; a bullet proof Tom's differential with "1000 horsepower" Drive Shaft Shop aluminum half shafts; etc. The body is widened six inches for bigger tires and to keep from having to narrow the suspension which creates too many angles during travel and affects camber gain. The rear tires are 345s on 13 inch wide X 18 inch HRE wheels. The front is equally as modified -- Woodward front steer rack, ATS spindles, custom roller bearing control arms, etc. As Tyler said, we have been working on our cars a long time with the hopes the effort will be worth while. Like Tyler, my car will be streetable, but with a bias toward the track.

Pappy

[CamaroAJ]

what has two thumbs and wants to see more pictures? this guy.

[Teetoe_Jones]

Originally Posted by Vince@MSperfab

hey Pap, you have any build threads of your camaro project, love to see it.

Vince

Originally Posted by CamaroAJ

what has two thumbs and wants to see more pictures? this guy.

Here ya go you lazy bastards. It's a Corvette though, not a Camaro.

https://lateral-g.net/forums/showthread.php4?t=21031
https://lateral-g.net/forums/showthread.php4?t=20865

Tyler